"I have made the difficult decision to retire as of today," Harrison posted. "My love for my family and the need to be there for them outweighs my desire to play the game."

Harrison, 36, had been looking to sign with an NFL team following his release from the Cincinnati Bengals in March. He reportedly met with Arizona Cardinals officials this week, but the two sides couldn't reach an agreement on a contract.

Harrison, the 2008 AFC Defensive Player of the Year, entered the NFL with the Steelers in 2002 after playing at Kent State. After being released and then rejoining the Steelers in 2004, Harrison developed into one of the NFL's top linebackers, playing a leading role in Pittsburgh's Super Bowl wins in 2006 and 2009.

While establishing himself as one of the most feared defensive players in the game, Harrison also built a reputation as a controversial player. He was fined by the NFL several times during his career for illegal hits on quarterbacks. In 2010 alone he was fined a total of $125,000 for illegal hits and was suspended one game in 2011 for a helmet-to-helmet hit on Cleveland Browns quarterback Colt McCoy.

Harrison publicly criticized and lobbed insults at NFL Commissioner Roger Goodell for safety changes the league has imposed in recent years. Harrison said he had to change his approach to tackling in order to avoid the ire of the league's front office.

The Steelers released Harrison in March 2013, prompting his move to the Bengals. He had two sacks and 16 tackles with Cincinnati last season.

Harrison recorded 66 sacks and 472 tackles during his 11-year NFL career.